Tapping coal mines for rare-earth materials

May 23, 2024
Above: Michael Vanden Berg, a geologist with the Utah Geological Survey, examines a coal outcrop near Utah's old Star Point mine. Credit: Lauren Birgenheier


In a groundbreaking study led by the University of Utah, researchers have discovered elevated concentrations of rare earth elements (REEs) in active coal mines rimming the Uinta coal belt of Colorado and Utah.

This finding suggests that these mines, traditionally known for their coal production, could potentially serve as secondary sources for critical minerals essential for renewable energy and high-tech applications. "The model is if you're already moving rock, could you move a little more rock for resources towards energy transition? " Lauren Birgenheier, an associate professor of geology and geophysics, explains, In those areas, we're finding that the rare earth elements are concentrated in fine-grain shale units, the muddy shales that are above and below the coal seams."

Lauren Birgenheier

This research was conducted in partnership with the Utah Geological Survey and Colorado Geological Survey as part of the Department of Energy-funded Carbon Ore, Rare Earth and Critical Minerals project, or CORE-CM. The new findings will form the basis for a grant request of an additional $9.4 million in federal funding to continue the research.

"When we talk about them as 'critical minerals,' a lot of the criticality is related to the supply chain and the processing," said Michael Free, a professor metallurgical engineering and the principal investigator on the DOE grant. "This project is designed around looking at some alternative unconventional domestic sources for these materials."

The U-led study was published last month in the journal Frontiers in Earth Science. Team members included graduate students Haley Coe, the lead author, and Diego Fernandez, a research professor who runs the lab that tested samples.

“The goal of this phase-one project was to collect additional data to try and understand whether this was something worth pursuing in the West,” said study co-author Michael Vanden Berg, Energy and Minerals Program Manager at the Utah Geological Survey. “Is there rare earth element enrichment in these rocks that could provide some kind of byproduct or value added to the coal mining industry?”

Haley Coe, U geology graduate student, inspects drilling cores. Photo Credit: Lauren Birgenheier.

“The coal itself is not enriched in rare earth elements,” Vanden Berg said. “There's not going to be a byproduct from mining the coal, but for a company mining the coal seam, could they take a couple feet of the floor at the same time? Could they take a couple feet of the ceiling? Could there be potential there? That's the direction that the data led us.”

To gather samples, the team worked directly with mine operators and examined coal seam outcrops and processing waste piles. In some cases, they analyzed drilling cores, both archived cores and recently drilled ones at the mines. The team entered Utah mines to collect rock samples from the underground ramps that connect coal seams.

The study targeted the coal-producing region stretching from Utah’s Wasatch Plateau east across the Book Cliffs deep into Colorado. Researchers analyzed 3,500 samples from 10 mines, four mine waste piles, seven stratigraphically complete cores, and even some coal ash piles near power plants.

The study included Utah’s active Skyline, Gentry, Emery and Sufco mines, recently-idled Dugout and Lila Canyon mines in the Book Cliffs, and the historic Star Point and Beaver Creek No. 8 mines. The Colorado mines studied were the Deserado and West Elk.

Discover more about this groundbreaking research by visiting the full article by Brian Maffly at @The U.

Read more about this story at KUER.